This invention relates generally to pressure compensated load responsive control valves of direction control type, which in control of a load, while using a control load pressure sensing passage, automatically maintain pump discharge pressure at a level higher, by a constant pressure differential, than the pressure required by the controlled load, by either bypassing excess pump flow to system reservoir, or by varying displacement of the pump.
In more particular aspects this invention relates to load responsive direction control valves having load sensing ports and a control float position, in which the motor ports are connected to each other and to system reservoir and pump port is isolated.
The direction control valves with float position, in which the motor ports are connected to each other and to system reservoir, while pump is isolated, are well known in the art, and have been used in conventional fluid power circuits for many years. Those valves in the float position permit the free transfer between the motor ports and system reservoir, permitting the tool to float without using any of the pump flow. The use of such valves in a load responsive system presents new problems of dealing with load sensing ports in the float position.